We are often asked, “what makes the popping sound during an adjustment?”
That is a great question. So let’s start off by explaining what we are looking and trying to accomplish with an adjustment. When the joints are assessed/palpated, we are looking for joints that don’t move as well as they should. This lack of motion then causes a trickle-down effect on surrounding tissues by causing undue strain. The adjustment to that joint is a very targeted rapid opening of the joint space; which is filled with joint fluid (synovial fluid) and surrounded by a joint capsule. When that rapid impulse occurs, tiny little bubbles of air are squeezed out of the end of the bones. Simultaneously the joint capsule is being stretched and narrowed, causing those tiny bubbles to coalesce, forming a big bubble. A split second later, as the opening grows bigger, that large bubble pops, giving the classic “pop” of an adjustment.
The measure of a truly successful manipulation is increased movement in that joint. Remember, when we are looking for areas that need to be adjusted, we are looking for joints that don’t move enough.
Unfortunately people often think hearing a pop is necessary for a successful adjustment. But in order for that pop to occur, the joint has to be able to open far enough that the big air pocket can pop. Some joints are either too restricted for that to occur or just aren’t big enough or can move far enough to get to that point.
Adding to the confusion is the fact that after a “pop” there is a period of increased pain-relief. This feeling comes from endorphins (natural pain-killers produced by your body) that are released as a result of that pop in the joint. Sound goods, and it isn’t bad, but if the only thing that happened was an endorphin release, the pain-relief would wear off after a short period. The lasting pain-relief/improved function comes from the joint moving properly again.
On the flip side, people are often worried that they “popped a joint out of place,” when they are out and about and hear/feel a joint pop. Have no fear, as long as there isn’t lasting pain, you just moved in a manor that stretched a joint and caused that air pocket to pop. Enjoy the free endorphin rush!
So, the “popping” sound comes from a pocket of air inside joints that doesn’t have a long term benefit. Nor is necessary for a successful adjustment, as long as motion is restored. It also doesn’t indicate if a bone has been “popped in or out of place.” But, it is a nice benefit when it does occur.
Thomas Cotter, DC, DACRB